The overall goal of this Program is to develop safe and effective topical microbicides for intravaginal or rectal use that will block sexual transmission of human immunodeficiency virus (HIV) and other sexually transmitted diseases. The program focuses on a novel family of candidate microbicides based on the parent compound, sodium dimandelic acid ether (SAMMA). The applicant has found that SAMMA has excellent anti-HIV and anti-herpes simplex virus (HSV) activity, while exhibiting no cytotoxicity in tissue culture. Preliminary studies suggest that SAMMA inhibits viral entry, but it is unique among other inhibitors of entry because it contains no sulfur. Project II focuses on defining the mechanism of activity of SAMMA and structural derivatives against HSV. There are several reasons to focus on HSV in the development of topical microbicides. HSV is a major co-factor in HIV transmission and recent epidemiological studies highlight the urgent need for HSV control if HIV is to be successfully combated. HSV ulcerative lesions enhance acquisition of HIV-1. At a molecular level, HSV infection may induce the expression of pro-inflammatory cytokines that are known to induce HIV-1 replication and may activate cellular pathways, which may enhance HIV-1 replication. In addition, mouse studies of genital herpes are an excellent surrogate small animal model for evaluating the anti-viral and local immunological effects of candidate agents. Also, recent studies from our laboratories clearly demonstrate parallels in the pathways of invasion of HSV and HIV and in the anti-viral activity of candidate agents. Thus, understanding the mechanism of anti-HSV activity of this family of drugs may shed light on mechanism of anti- HIV activity .The first aim of Project II is to evaluate the efficacy, cytotoxicity and mechanisms of activity of SAMMA and chemical derivatives against HSV using primary and permanent human cell culture systems. In Aim 2, the applicant will isolate viruses resistant to SAMMA or lead derivatives. Resistant variants will provide insight into the mechanism of anti-viral activity of the compound and the potential for generating resistant virus in humans. The third aim will focus on identifying the viral and cellular factors important in HSV-induced enhancement of HIV replication and the effects of SAMMA on this phenomenon. The knowledge gained from these studies will provide important data for advancing SAMMA or one of its lead derivatives to clinical trials.